      <h2> Overview.</h2>
The definitions described in this section are used at ECMWF for special
purposes.
      <p> Element KSEC1(24) is set to 1 if an ECMWF local use
definition is required or has been found in a GRIB message; element
KSEC1(37) indicates which definition it is. </p>
      <p> If KSEC1(24) is set to 0, no local use definition is present
in the message. </p>
      <p> Currently, the following definitions exist: </p>
      <ul>
        <li> <a href="localDefinition1.html">Definition 1</a> - MARS
labelling or ensemble forecast data </li>
        <li> <a href="localDefinition2.html">Definition 2</a> -
Cluster means and standard deviations </li>
        <li> <a href="localDefinition3.html">Definition 3</a> -
Satellite image data </li>
        <li> <a href="localDefinition4.html">Definition 4</a> - Ocean
model data </li>
        <li> <a href="localDefinition5.html">Definition 5</a> -
Forecast probability data </li>
        <li> <a href="localDefinition6.html">Definition 6</a> -
Surface temperature data </li>
        <li> <a href="localDefinition7.html">Definition 7</a> -
Sensitivity data </li>
        <li> <a href="localDefinition8.html">Definition 8</a> - ECMWF
re-analysis data </li>
        <li> <a href="localDefinition9.html">Definition 9</a> -
Singular vectors and ensemble perturbations </li>
        <li> <a href="localDefinition10.html">Definition 10</a> - EPS
tubes </li>
        <li> <a href="localDefinition11.html">Definition 11</a> -
Supplementary data used by the analysis </li>
        <li> <a href="localDefinition13.html">Definition 13</a> - Wave
2D spectra direction and frequency </li>
        <li> <a href="localDefinition14.html">Definition 14</a> -
Brightness temperature </li>
        <li> <a href="localDefinition15.html">Definition 15</a> -
Seasonal forecast data </li>
        <li> <a href="localDefinition16.html">Definition 16</a> -
Seasonal forecast monthly mean data </li>
        <li> <a href="localDefinition17.html">Definition 17</a> -
Surface temperature or sea-ice data </li>
        <li> <a href="localDefinition18.html">Definition 18</a> -
Multi-analysis ensemble data </li>
        <li> <a href="localDefinition19.html">Definition 19</a> -
Extreme forecast index data </li>
        <li> <a href="localDefinition20.html">Definition 20</a> - 4D
variational increments </li>
        <li><a href="localDefinition21.html">Definition 21</a> -
Sensitive area predictions </li>
        <li><a href="localDefinition22.html">Definition 22</a> -
Coupled atmospheric, wave and ocean models (with hindcast support) </li>
        <li><a href="localDefinition23.html">Definition 23</a> -
Coupled atmospheric, wave and ocean means (with hindcast support) </li>
        <li><a href="localDefinition24.html">Definition 24</a> -
Satellite image simulation </li>
        <li><a href="localDefinition25.html">Definition 25</a> - 4DVar
model errors</li>
        <li><a href="localDefinition26.html">Definition 26</a> - MARS
labelling or ensemble forecast data (with hindcast support)</li>
        <li><a href="localDefinition27.html">Definition 27</a> -
Forecasting Systems with Variable Resolution (Obsolete)</li>
        <li><a href="localDefinition30.html">Definition 30 </a> -
Forecasting Systems with Variable Resolution</li>
        <li><a href="localDefinition31.html">Definition 31 </a> -
EUROSIP products</li>
        <li><a href="localDefinition50.html">Definition 50</a> - Member
State data </li>
        <li><a href="localDefinition190.html">Definition 190</a>
-Multiple ECMWF local definitions </li>
        <li><a href="localDefinition191.html">Definition 191</a> - Free
format data descriptor data </li>
        <li><a href="localDefinition192.html">Definition 192</a> -
Multiple ECMWF local definitions </li>
      </ul>
      <h2> Octets in section 1</h2>
The relation between the octets (bytes) in section 1 of a GRIB product
and the elements in the array KSEC1 is illustrated below.
      <p>
      <table border="3">
        <caption>
        <center>
        <h2> Octets in section 1</h2>
        </center>
        </caption><tbody>
          <tr>
            <th> Octet</th>
            <th> KSEC1 element</th>
            <th> Comments</th>
          </tr>
          <tr>
            <td> 1-3</td>
            <td> -</td>
            <td> Length of section 1</td>
          </tr>
          <tr>
            <td> 4</td>
            <td> 1</td>
            <td><a
 href="http://www.ecmwf.int/services/archive/d/table/grib_table_2_versions/">
Version
number of code table 2</a></td>
          </tr>
          <tr>
            <td> 5</td>
            <td> 2</td>
            <td><a href="/publications/manuals/libraries/gribex/wmoCodeTable0.html"> Identification
of centre (ECMWF = 98)</a></td>
          </tr>
          <tr>
            <td> 6</td>
            <td> 3</td>
            <td> Generating process identification number</td>
          </tr>
          <tr>
            <td> 7</td>
            <td> 4</td>
            <td> Grid definition</td>
          </tr>
          <tr>
            <td> 8</td>
            <td> 5</td>
            <td><a href="/publications/manuals/libraries/gribex/wmoCodeTable1.html"> Section 2/3
indication flag</a></td>
          </tr>
          <tr>
            <td> 9</td>
            <td> 6</td>
            <td><a href="/publications/manuals/libraries/tables/localTable128.html"> Parameter
indicator</a></td>
          </tr>
          <tr>
            <td> 10</td>
            <td> 7</td>
            <td><a href="/publications/manuals/libraries/gribex/wmoCodeTable3.html"> Level
indicator/satellite identifier</a></td>
          </tr>
          <tr>
            <td> 11</td>
            <td> 8</td>
            <td> Height/pressure of level</td>
          </tr>
          <tr>
            <td> 12</td>
            <td> 9</td>
            <td> Height/pressure of level</td>
          </tr>
          <tr>
            <td> 13</td>
            <td> 10</td>
            <td> Year</td>
          </tr>
          <tr>
            <td> 14</td>
            <td> 11</td>
            <td> Month</td>
          </tr>
          <tr>
            <td> 15</td>
            <td> 12</td>
            <td> Day</td>
          </tr>
          <tr>
            <td> 16</td>
            <td> 13</td>
            <td> Hour</td>
          </tr>
          <tr>
            <td> 17</td>
            <td> 14</td>
            <td> Minute</td>
          </tr>
          <tr>
            <td> 18</td>
            <td> 15</td>
            <td><a href="/publications/manuals/libraries/gribex/wmoCodeTable4.html"> Time unit
indicator</a></td>
          </tr>
          <tr>
            <td> 19</td>
            <td> 16</td>
            <td> Time period</td>
          </tr>
          <tr>
            <td> 20</td>
            <td> 17</td>
            <td> Time period</td>
          </tr>
          <tr>
            <td> 21</td>
            <td> 18</td>
            <td><a href="/publications/manuals/libraries/gribex/wmoCodeTable5.html"> Time range
indicator</a></td>
          </tr>
          <tr>
            <td> 22-23</td>
            <td> 19</td>
            <td> Number of products in an average</td>
          </tr>
          <tr>
            <td> 24</td>
            <td> 20</td>
            <td> Number of products missing from an average</td>
          </tr>
          <tr>
            <td> 25</td>
            <td> 21</td>
            <td> Century</td>
          </tr>
          <tr>
            <td> 26</td>
            <td> 22</td>
            <td><a href="/publications/manuals/libraries/gribex/wmoCodeTable0.html"> Sub-centre
identifier</a></td>
          </tr>
          <tr>
            <td> 27-28</td>
            <td> 23</td>
            <td> Decimal scale factor</td>
          </tr>
          <tr>
            <td> -</td>
            <td> 24</td>
            <td> Flag to indicate local usage in section 1</td>
          </tr>
          <tr>
            <td> 29-40</td>
            <td> 25-36</td>
            <td> Zero</td>
          </tr>
          <tr>
            <td> 41</td>
            <td> 37</td>
            <td><a href="/publications/manuals/libraries/gribex/localGRIBUsage.html"> ECMWF local
GRIB usage definition identifier*</a></td>
          </tr>
          <tr>
            <td> 42</td>
            <td> 38</td>
            <td><a
 href="http://www.ecmwf.int/services/archive/d/table/grib_class/"> Class</a></td>
          </tr>
          <tr>
            <td> 43</td>
            <td> 39</td>
            <td><a
 href="http://www.ecmwf.int/services/archive/d/table/grib_type/"> Type</a></td>
          </tr>
          <tr>
            <td> 44-45</td>
            <td> 40</td>
            <td><a
 href="http://www.ecmwf.int/services/archive/d/table/grib_stream/">
Stream</a></td>
          </tr>
          <tr>
            <td> 46-49</td>
            <td> 41</td>
            <td> Version number or experiment identifier</td>
          </tr>
        </tbody>
      </table>
      </p>
      <p> * Local definition numbers 192 to 255 inclusive will never be
used to define ECMWF local extensions to section 1, GRIB code. They are
free to be defined and used by Member States.
